Process of concentrating ores and minerals by flotation



Patented Feb. 14, 1928.

UNITED STATES PATENT OFFICE;

WILLIAM A. DOUGLASS, OF PENNS GROVE, NEW JERSEY, ASSIGNOR TO E. I. DUIONl- DE NEMOURS & COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OFDEL- AWARE.

PROCESS OIE GONCENTRATING ORES AND MINERALS BY FLOTA'IION.

N Drawing.

This invention relates to the recovery of valuable ores and minerals byflotation, and comprises more particularly the concentration of suchores and minerals by means of a certain class of organic flotationagents.

It is one of the objects of the present invention to carry out flotationprocesses in an eficient manner by using as the flotation agent one of aclass of organic compounds having highly selective properties when soused. It is-a further object to carry out the flotation processes byusing flotation agents which are suitable for use in neutral, alkalineor acid flotation circuits without decoinplosition of the flotationagents.

ave discovered that these and other ob jects may be accomplished byusing in a flotation process organic derivatives of trithio carbonicacid as the flotation agents. These compounds are characterized byhaving the following general structural formula:

where R and R are orgamc groups. R and B may represent the same ordifferent organic groups.

A specific example of a derivative in which R and R are alkyl groups isdiethyl ester of trithio carbonic acid having the following formula:

' s,-o,n

SCaHt somooocm.

Dibenzoyl trithio carbonate having the formula:

SCHgCOO 02115 is an example of a derivative in which R and R are acylgroups. Diethyl thiol ester Application filed October 25, 1926. SerialNo. 144,193.

of thion carbonyl disulfide having the following formula:

S=(l]-SOgH5 18 still another type of derivative of trithio carbonate,wherein Ris an alkyl group and R is another trithio carbonate grouphaving the following formula:

S- SJ in which X represents an organic group such as an alkyl.

The various derivatives of trithio carbonic acid may be made in anysuitable manner. For instance, diethyl trithio carbonate can be made bydissolving 150 grams of potassium hydroxide in 250 cc. water, andsaturating this solution with hydrogen sulfide. To this solution isadded 150 grams of potasslum hydroxideand, when all is dissolved. 250grams of carbon bisulfide are added and the mixture agitated vigorouslyuntil all of the carbon disulfide goes into solution. The solution iswashed once with 300 cc. of alcohol. To the water layer containingpotassium trithio carbonate, 300 grams of ethyl bromide are slowly addedwith agitation and coolin The reaction product is washed with water andthe excess ethyl bromide removed by bubbling a current of air throughthe liquid. The resulting orange red liquid is pure diethyl trithiocarbonate.

This compound may loo-used as a flotation reagent in the followingmanner: 500 grams of minus 29 mesh Phelps-Dodge Corporation Copper Queenore are ground for 20 minutes in a pebble mill with 500 cc. of water,0.6 grams of lime and 0.025 grams of diethyl trithio carbonate. The limeand diethyl trithio carbonate are in the proportions of 2,4 lbs. and0.10 lb. respectively per ton of ore. The pulp from the pebble mill istransferred to a J anney laboratory flotation machine and a frothingagent (terpineol or pine oil) added. The pulp is diluted to about twoliters and a rougher concentrate removed for 10 minutes, water beingadded as needed. The following results were obtained:

% Cu in concentrate=7 .25.

% Cu in tailings=.22.

Extraction 87.6

Using Anaconda Table Tailings in a neutral circuit with diethyl trithiocarbonate as the flotation reagent in the proportion of 0.15 lbs. perton of ore, the following results were obtained:

% Cu in heads=1.88.

% Cu in concentrate 8.84:.

% Cu in tailings=0.18.

Total Cu recovered=92.3%.

The flotation reagents forming part of the present invention do notdecompose in an acid solution, and are therefore suitable for use inacid flotation circuits. .Using as the flotation reagent diethyl trithiocarbonate in the proportion of 0.15 lbs. per ton of ore in a circuitcontaining 7.0 lbs. of sulfuric acid per ton of ore, the followingresults were obtained:

% Cu in heads=l.88.

% Cu in concentrate=9.68.

% Cu in tailings=0.085.

Total Cu recovered=96.3%.

Dibenzoyl trithio carbonate can be made conveniently by treatingpotassium trithio carbonate in benzene suspension with benzoyl chloride,removing the heat of reaction by cooling. After filtration from thepotassium chloride and evaporation of the solvent, dibenzoyl trithiocarbonate is obtained as a yellowish orange oil.

When tested as a flotation reagent using an alkaline circuit accordingto the process described, the following results were obtained:

% Cu in concentrate=6.67.

% Cu in tailings=.20.

Extraction=89.2%.

Diethyl thiol ester of thioncarbonyl disulfide may be made by treatingthe mono ethyl ester of trithio carbonic acid (Chancel Jahres berichtfiir Chemie 1851, p. 513) with iodine. The orange brown oil which isformed, is washed with water and then dried with calcium chloride.

When tested as a flotation reagent using an alkaline circuit accordingto the process described, the following results were obtained:

% Cu in concentrate=6.60.

% Cu in tailings=0.24.

E xtraction=86.9%.

In illustrating the present process, reference has been madespecifically to certain ores and reagents, and to various specificconditions of operation. It will be understood that the present processis not limit- 7 ed to the specific substances or details of procedurementioned, but includes generally processes of recovering values fromores by flotation in which the flotation agents are members of the classof compounds described. For instance, it has been pointed out as beingdesirable to add a frothing agent in the specific examples noted.However, where the flotation agent itself has sutficient frothing power,the frothing agent may be omitted.

Any suitable modifications and changes may be made without departingfrom the spirit and scope of the invention.

I claim:

1. In the process of concentratin ores and minerals by flotation thestep which comprises subjecting the ore in the form of a pulp to a frothflotation operation in the presence of an organic derivative of trithiocarbonate.

2. In the process of concentrating ores and minerals by flotation, thestep which comprises subjecting the ore in the form of a pulp to a frothflotation operation in the presence of an organic derivative of trithiocarbonate having the following structural formula:

where R and R are organic groups.

3. In the process of concentrating ores and minerals by flotation, thestep which comprises subjecting the ore in the form of 1 a pulp to afroth flotation operation in the presence of an organic derivative oftrithio carbonate having the following structural formula:

SR =C/ in which R is an alkyl group and R is an

